Week -2

AIM:- To make a Simulink Model of Door Bell using Solenoid Block.

SOLENOID:- A Solenoid is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix. The coil can be arranged to produce a uniform magnetic field in a volume of space when a current is pass through it. The term solenoid was coined in1823 by Andre-Marie Ampere to designate a helical coil. In Engineering the term may also refer to a variety of transducer devices that convert energy into linear motion. The term is also often used to refer to a solenoid valve, an integrated device containing an electromechanical solenoid that actuates either a pneumatic value or hydraulic valve, or a solenoid switch, which is a specific type of Relay that internally uses an electromagnetic solenoid to operate an electric switch, for example, an automobile starter solenoid or linear solenoid, solenoid bolts, a type of electromechanical locking mechanism, also exist. In electromagnetic technology, a solenoid is an actuator assembly with a sliding ferromagnetic plunger inside the coil. Without power, the plunger extends for part of its length outside the coil; applying power pulls the plunger into the coil. Electromagnet with the fixed core is not considered solenoids.

Basic Component used to generate a simple Doorbell circuit is:

GIVEN CONDITION: IN the arrangement, when the switch is closed the electromagnet receives electrical power from the Battery and pulls the metal arm to hit the bell producing sound by creating a situation where the switch is closed for 2 secs and then released.

We have used the following Blocks in the model-

1. Pulse Generator:

The Pulse Generator block generates square wave pulses at regular intervals. The block waveform parameters, Amplitude, Pulse Width, Period, and Phase delay, determine the shape of the output waveform. The following diagram shows how each parameter affects the waveform.

2. Battery:

In Battery positive terminal is connected with the switch and the negative terminal is connected to “Electric Reference”.

3. Switch:

In the switch Block model, a switch is controlled by an external physical signal.

4. Solenoid Block:

Solenoid Block is connected with Switch and Battery and an electrical circuit will be formed.

The Solenoid Block represents the Electrical characteristics and generated force for the solenoid in the following figure:

The return spring is optional. To remove the effects of this spring from the model, set the spring constant parameter from 0 to 10.

To show the direction in which the solenoid acts the block icon changes dynamically based on the value of the Motion direction under the excitation parameter.

Port ‘C’ is connected with Mechanical Translation reference.

5. Ideal Translation Motion Sensor Block:

Ideal Translation Motion Sensor Block is connected with Solenoid Block ‘R’ to observe the Physical movement of the Plunger.

Connections R and C are mechanical translational conserving ports that connect the block to the nodes whose motion is being monitored. Connections V and P are physical signal output ports for velocity and position, respectively.

The block positive direction is from port R to port C. This means that the velocity is measured as v = vR – vC, where vR, vC are the absolute velocities at ports R and C, respectively.

Port C is connected with a Mechanical translational reference.

6. Scope:

The scope is connected with the Ideal Translation Motion Sensor to get the output. The real-time Scope block acquires data in chunks of size Number of samples from the real-time application that is executing on the target computer.

7. PS-Simulink Converter:

The PS-Simulink Converter block converts a physical signal into a Simulink output signal. Use this block to connect outputs of a Physical Network diagram to Simulink scopes or other Simulink blocks.

8. Simulink-Ps Converter:

This Block converts Simulink signals into a physical signal for operational use in the Model.

9. Electrical Reference Block:

The Electrical Reference block represents an electrical ground. Electrical conserving ports of all the blocks that are directly connected to the ground must be connected to an Electrical Reference block. A model with electrical elements must contain at least one Electrical Reference block.

10. Mechanical Translation Reference Block:

The Mechanical Rotational Reference block represents a reference point, or frame, for all mechanical rotational ports. All rotational ports that are rigidly clamped to the frame (ground) must be connected to a Mechanical Rotational Reference block.

11. Solver Configuration:

Each physical network represented by a connected Simscape block diagram requires solver settings information for simulation. The Solver Configuration block specifies the solver parameters that your model needs before you can begin the simulation.

OBJECTIVES:

For DoorBell- Create a situation where the switch is closed for 2 sec and then released. Observe the physical movement of the plunger.

SIMULINK MODEL:-

PROCEDURE:

• Open the Matlab, type Simulink in the command window or Select Simulink in the home bar.
• To create a doorbell in Simulink we need Simulink blocks such as Solenoid, Signal builder, Ideal translational motion sensor, switch, battery, electrical reference, mechanical translational reference, solver configuration, Scopes and PS-Simulink, Simulink-PS converters.
• Parameters for Plus Generator
  

  

• Parameters for Solenoid Blocks

  
• After inserting on the screen connect them as required.
• Goto signal builder, and plot the graph.
• For every 2sec of time, the voltage should fluctuate till a stop time of 10 sec.

Output From Scope:-

Output From Scope1:-

2. THERMISTOR

Theory:-

A thermistor is a resistance thermometer or a resistor whose resistance is dependent on temperature. The term is a combination of “thermal” and “resistor”. It is made of metallic oxides, pressed into a bead, disk, or cylindrical shape and then encapsulated with an impermeable material such as epoxy or glass.

There are two types of thermistors: Negative Temperature Coefficient (NTC) and Positive Temperature Coefficient (PTC). With an NTC thermistor, when the temperature increases, resistance decreases. Conversely, when temperature decreases, resistance increases. This type of thermistor is used the most.

A PTC thermistor works a little differently. When temperature increases, the resistance increases, and when temperature decreases, resistance decreases. This type of thermistor is generally used as a fuse.

Typically, a thermistor achieves high precision within a limited temperature range of about 50ºC around the target temperature. This range is dependent on the base resistance.

Procedure :

• First, we give the input signal with the help of a repeating sequence stair block.
• The input signal block is connected to the 's' port of the controlled temperature source block with the help of a Simulink-ps converter. the 'B' port of the controlled temperature source is connected to the 'A' port(net heat flows through port A) of the thermistor.
• A scope is connected to the input signal to observe the input.
• Then we make a thermistor block and connect a battery to it as a voltage source.
• A conditional switch block with 2 constant blocks of value '0' and '1' is connected to the "v" port of the voltage sensor.

• The threshold of the switch is calculated with the help of thermistor equation
• The conditional switch block is connected to a scope to display the graph and the output of the switch is connected to a lamp. the lamp glows red if the resistance across is less than the switching threshold meaning the fan is off, if the resistance across is higher than the switching threshold the lamp glows green meaning the fan is on.
• Thermal reference and electrical reference is connected to provide earthing.
• The initial stop time is given as 20 sec.

Parameters:-

• Repeating sequence stair.
  
  

• Switch Parameter.
  
  

Results:-

Simulink Model-

The fan is off when the temperature is less than 25 degrees celsius and the fan is on when the temp is greater than 25 degrees celsius.

1. Temperature below 25 degrees Celsius, the fan is OFF.
   
   
   
   Output Scope:-
   
   0 in the Graph indicates the fan is off.
   
   
2. Temperature above 25 degrees Celsius, the fan is ON.
   
   
   
   Output Scope:-
   
   1 in the graph indicates the fan is ON.